Hidden Traces on the Forest Floor: Exploring the Phasianidae Family of Sumatra

Under the dense canopy of Sumatra’s tropical forests, on the shaded and humid forest floor, thrives a diverse array of birds from the Phasianidae family that often go unnoticed. This group includes graceful, large-sized pheasants; brightly colored peacocks; junglefowl, the ancestors of domestic chickens; and shy partridges. Some species are endemic to mountainous regions, while others inhabit lowland forests, yet they all share a common trait: a strong dependence on intact forest ecosystems. Their presence is often revealed only through distinctive calls or faint tracks among the leaf litter.

This article aims to introduce readers to the richness of Phasianidae in Sumatra, covering their morphological characteristics, habitats, behaviors, and conservation status based on the most recent data. Amid the threats of deforestation and habitat fragmentation, several species are now considered vulnerable and require urgent attention. By understanding their uniqueness and ecological roles, it becomes evident that these ground-dwelling birds are not merely forest inhabitants but integral components of Sumatra’s ecological balance, deserving of protection.

1. Blue-breasted Quail / IUCN Status: Least Concern (LC)

Photo by Wikipedia

Synoicus chinensis, commonly known as the Blue-breasted Quail, King Quail, or Chinese Painted Quail, is a small bird belonging to the order Galliformes and the family Phasianidae. According to BirdLife International, this species has a very wide distribution, ranging from South Asia and Southeast Asia to China, Australia, and other regions of Oceania. It typically inhabits open habitats such as grasslands, scrublands, agricultural fields, and shallow wetlands with low vegetation, which provide protection from predators. Its small size and ground-dwelling behavior make it difficult to detect in the wild.

Morphologically, this species exhibits pronounced sexual dimorphism. Males display a striking bluish-grey breast with a chestnut-colored underbelly, whereas females are dominated by dull brown plumage with lined patterns that serve as camouflage. This distinction reflects adaptive strategies in small ground-dwelling birds, where males use conspicuous coloration for sexual selection, while females rely on concealment to enhance survival, particularly during the reproductive period (BirdLife International, 2024).

2. Chestnut-necklaced Partridge / IUCN Status: Vulnerable (VU)

Chesnut-neckleaced Partridge/Photo credit by LetsBirding Sumatra

Tropicoperdix charltonii, or the Chestnut-necklaced Partridge, is a medium-sized ground-dwelling bird (26–32 cm) from the family Phasianidae, distributed across the Sunda region, including Sumatra and Borneo. According to BirdLife International, this species typically inhabits lowland forests below 300 meters and is terrestrial, often observed walking on the forest floor either alone or in small groups. Taxonomically, it comprises two main subspecies: T. c. charltonii in the Thai–Malay Peninsula and T. c. atjenensis, which is endemic to Sumatra. T. c. graydoni from Borneo is sometimes treated as a separate species due to notable morphological differences.

Morphologically, the species is generally brown, with a distinctive chestnut-colored breast band on the upper chest that is not prominently patterned, serving as a key field identification feature. The rest of the body is dominated by brown tones with fine patterns that aid camouflage on the leaf-littered forest floor. Like other galliforms, it has a compact body and strong legs adapted for walking and foraging on the ground. In Sumatra, T. c. atjenensis was first recorded during the 1936–1939 expedition and was not observed again for over 80 years, leading to speculation that it might be extinct in the wild. Its rediscovery in 2023 in Aceh confirmed its presence in fragmented lowland forests at approximately 150 meters elevation, with the primary threat being habitat loss due to forest conversion into plantations (Wahyudi et al., 2023).

3. Ferruginous Partridge / IUCN Status: Near Threatened (NT)

Ferruginous Partridge/Photo credit by Bksda Aceh/FFI

Caloperdix oculeus, or the Ferruginous Partridge, is a medium-sized ground-dwelling bird (23–27 cm) from the family Phasianidae, distributed across the Sunda region, including Sumatra and Borneo. According to BirdLife International, this species comprises three subspecies, two of which occur in this region: C. o. borneensis in Borneo and C. o. ocellatus in Sumatra. The species is generally patchily distributed and considered uncommon, inhabiting both primary and secondary forests, including areas with bamboo, up to elevations of less than 1,000 meters. Behaviorally, it is primarily terrestrial, often observed alone or in pairs, actively foraging on the forest floor.

Morphologically, the species is characterized by a predominantly bright rufous coloration on the head, neck, and breast, with a paler throat and belly. A distinct dark line runs through the eye, serving as a key diagnostic feature. The flanks, wings, and mantle display barred patterns, varying between subspecies: black-and-white in borneensis and black-and-cream in ocellatus. The wings are pale brown with conspicuous black spots, while the back and upper tail coverts are darker with rufous barring. The main threat to this species is habitat loss due to deforestation, which has led to population declines across parts of its range.

4. Great Argus / IUCN Status: Vulnerable (VU)

Great Argus/Photo credit by Bksda Aceh/FFI

Argusianus argus, or the Great Argus, is a large bird from the family Phasianidae, distributed across the Sunda region, including Sumatra, Peninsular Malaysia, and Borneo. This species exhibits pronounced sexual dimorphism, with males reaching a total length of 150–200 cm, including their exceptionally long tail, while females are significantly smaller at around 74–75 cm. According to BirdLife International, it consists of two main subspecies: A. a. argus (Sumatra and Peninsular Malaysia) and A. a. grayi (Borneo). Its primary habitat includes primary forests and mature secondary forests in interior regions, generally up to elevations below 1,000 meters in Sumatra and up to 1,800 meters in Borneo. The species is terrestrial and elusive, typically encountered alone or as a single male accompanied by several females.

Morphologically, the Great Argus is distinguished by its large body, elongated tail, and bare cobalt-blue skin on the head and neck, which appears duller in females, along with a small crest. The underparts are reddish-brown, while the upperparts are brown with distinctive spotted patterns. The subspecies grayi has a more orange-toned breast and greyer upperparts with white spots. This species is well known for its unique courtship display, in which the male clears sections of the forest floor to create a display ground used to attract females. Its vocalisation is distinctive, consisting of loud “KWOW” calls repeated at intervals or “KA-WOO” sounds often heard during display. Although still relatively common in certain habitats, the species faces significant threats from habitat loss due to deforestation, highlighting the need for sustainable forest management.

5. Long-billed Partridge / IUCN Status: Near Threatened (NT)

Long-billed Partridge

Rhizothera longirostris, or the Long-billed Partridge, is a medium-sized ground-dwelling bird (30–35 cm) from the family Phasianidae, distributed across the Sunda region, including Sumatra, Borneo, and Peninsular Malaysia. According to BirdLife International, this species is monotypic and considered rare, with a localised distribution. Its primary habitat consists of primary forest and mature secondary forest up to elevations of around 1,300 meters. The species is terrestrial and is typically encountered alone or in pairs, although it may fly to low branches when disturbed.

Morphologically, this species is characterised by a rufous face and underparts, a darker crown, and upperparts patterned in brown and black. Its most distinctive feature is a long, strong, and downcurved bill. Males possess a broad grey breast band, as well as similar colouring on the rump and upper tail coverts, whereas females lack these features. Juveniles resemble females but appear duller, with pale streaking on the throat, breast, and mantle, along with faint barring on the flanks. Its vocalisation consists of a rapid and repetitive two-note “kan-king” call, often delivered in duet. Compared to similar species such as Caloperdix oculeus, the Long-billed Partridge is larger, has a longer bill, and lacks the bold black-and-white barring on the flanks.

6. Malayan-crested Fireback / IUCN Status: Vulnerable (VU)

 Malayan-crested Fireback/ Photo credit by Hutan Harimau

Lophura rufa, or the Malayan Crested Fireback, is a large ground-dwelling bird from the family Phasianidae, distributed across the Sunda region, including Peninsular Malaysia and Sumatra. Males measure around 65–70 cm in length, while females are smaller at about 56–57 cm. This species is monotypic and is often considered closely related to Lophura ignita (Bornean Crested Fireback), particularly due to historical reports of hybridisation in southern Sumatra, such as in Lampung and Jambi, which are geographically close to Bangka Island. However, recent population studies indicate that most populations in Sumatra remain pure L. rufa. According to BirdLife International, the species is considered uncommon and inhabits primary and mature secondary forests up to elevations of around 600 meters. It is shy, terrestrial, and usually encountered alone or in small groups.

Morphologically, males are predominantly dark bluish-black, characterised by a distinctive coppery-red rump, white central tail feathers, white streaks along the flanks, and striking blue facial skin. Females and juveniles are mainly rufous-brown, with a paler throat and lighter feather edges on the breast and flanks, as well as less conspicuous blue facial skin compared to males. The species exhibits a characteristic display behaviour, producing audible wing-flapping sounds at close range, along with vocalisations such as a guttural “UKHT” alarm call and softer “keep” or “chek” calls when in groups. The primary threat to this species is the loss of lowland forest habitat due to deforestation, which has led to population declines in parts of its range.

7. Red-billed Partridge / IUCN Status: Least Concern (LC)

 Red-billed Partridge/Photo credit by LetsBirding Sumatra

Arborophila rubrirostris, or the Red-billed Partridge, is a medium-sized ground-dwelling bird (around 29 cm) from the family Phasianidae, endemic to Sumatra and considered monotypic. According to BirdLife International, this species is fairly common in suitable habitats, particularly in montane forests at elevations of 900–2,500 meters. It is terrestrial in behaviour and is usually encountered alone or in small groups, favouring moist forest floors densely covered with vegetation.

Morphologically, this species is easily recognised by its bright red bill and legs, which create a strong contrast. The head is black, sometimes with a white throat and a subtle supercilium, and it features a broad rufous-brown breast band marked with white spots. The belly is greyish-white with black patterning, while the flanks show a scaled appearance formed by a combination of black and white. The upperparts are dark brown with fine scaling. Its vocalisation consists of a repeated two-syllable call, “wa-hu,” delivered at a slower rhythm, often in duet, where one individual produces the main note while the other responds with a descending tone. The combination of a red bill, dark head, and rufous-brown breast band serves as the key distinguishing feature from other partridge species in Sumatra.

8. Red Junglefowl / IUCN Status: Least Concern (LC)

Red Junglefowl/Photo credit by LetsBirding Sumatra

Gallus gallus, or the Red Junglefowl, is a large ground-dwelling bird from the family Phasianidae, widely distributed across South and Southeast Asia. Males measure about 65–78 cm in length, while females are smaller at around 41–46 cm. This species comprises several subspecies, with two to three occurring in Indonesia: G. g. spadiceus (northern Sumatra and mainland Southeast Asia), G. g. bankiva (southern Sumatra to Bali), and populations in Borneo and Sulawesi that are thought to be introduced and in some cases mixed with other subspecies. According to BirdLife International, the species is fairly common and occurs in a wide range of habitats, including primary forest, secondary forest, scrub, disturbed areas, and agricultural land, from lowland areas up to about 900 meters in Sumatra. It is terrestrial and typically encountered alone or in small groups.

Morphologically, males are characterised by a prominent red comb and wattles, white ear patches, orange-red hackles, and a long, metallic green tail, with darker underparts. The subspecies bankiva generally shows more extensive red coloration with reduced white ear patches. Females and juveniles are predominantly brown, with streaked patterns and pale feather edges that provide effective camouflage. Its vocalisation is a loud, harsh call described as “errch-KRROO-doo,” resembling that of domestic chickens but with a higher pitch and a shorter terminal note. This species frequently interacts and hybridises with domestic chickens, resulting in morphological variation in some wild populations; however, true wild individuals typically retain consistent and distinctive plumage patterns.

9. Roll’s Partridge / IUCN Status: Least Concern (LC)

Roll’s Partridge/Photo credit by LetsBirding Sumatra

Arborophila rolli, or Roll’s Partridge, also known as the Tan-breasted Partridge, is a medium-sized ground-dwelling bird (around 28 cm) from the family Phasianidae, endemic to northern Sumatra. This species is monotypic and has a restricted distribution in mountainous regions such as the Batak Mountains and Simalungun, at elevations of approximately 500–2,000 meters. According to BirdLife International, it is considered uncommon and inhabits submontane to montane forests, particularly in areas with dense undergrowth. It is terrestrial in behaviour and is typically encountered alone or in small groups.

Morphologically, this species has a dark head, with the forehead, crown, and nape in deep brown tones, along with white patches on the lores and cheeks, and a fine white line on the throat. The underparts are buffy grey, becoming paler towards the belly, while the flanks show bold black barring. The upperparts are brown with fine black streaking, and the wings are brown with chestnut and black markings. The bill is black. Its vocalisation resembles that of the Chestnut-bellied Partridge, consisting of repeated calls typical of the genus Arborophila. This species can be distinguished from Tropicoperdix charltonii by its greyer underparts and the bold barring on the flanks.

10. Roulroul / IUCN Status: Vulnerable (VU)

Male Roulroul/Photo credit by Bksda Aceh/FFI

Female Roulroul/Photo credit by Bksda Aceh/FFI

Rollulus rouloul, commonly known as the Roulroul or Crested Partridge, is a small ground-dwelling bird (around 25 cm) from the family Phasianidae, distributed across the Sunda region, including Sumatra, Borneo, and Peninsular Malaysia. This species is monotypic and, according to BirdLife International, is considered uncommon to locally fairly common, although it is often difficult to observe due to its shy behaviour. Its primary habitat consists of primary forest and mature secondary forest up to elevations of around 1,300 meters. The species is terrestrial and is usually encountered alone, in pairs, or in small groups, and will scatter noisily when disturbed.

Morphologically, this species has a rounded body with striking red bare skin around the eyes and red legs. Males are predominantly metallic bluish-green, with a distinctive red crest and a white patch on the forehead, while females are green with rufous-brown wings and a grey head. Juveniles resemble females but appear duller. Under low light conditions, the plumage may appear uniformly dark. Its vocalisation is a high-pitched, whistling call that rises and then falls (“swee”), lasting about 1.5 seconds and repeated at regular intervals.

11. Salvadori’s Pheasant / IUCN Status: Near Threatened (NT)

Male Salvadori’s Pheasant/Photo credit by Hutan Harimau.

Female Salvadori’s Pheasant/Photo credit by Hutan Harimau.

Lophura inornata, or Salvadori’s Pheasant, is an endemic bird of Sumatra measuring 46–55 cm in length. It comprises two subspecies: inornata (southern and central Sumatra) and hoogerwerfi (northern Sumatra), the latter sometimes treated as a separate species due to subtle morphological differences. This species is considered uncommon and inhabits montane forests at elevations of 800–2,200 meters, particularly in relatively undisturbed primary and mature secondary forests. It is terrestrial, highly elusive, and typically encountered alone, spending most of its time on the forest floor foraging on seeds, fallen fruits, and small invertebrates, with a strong dependence on intact forest ecosystems (BirdLife International).

Morphologically, this species is readily identified by its red facial skin with a yellow spot behind the eye and a pale bill. Males are dark bluish-black with a metallic sheen and bluish feather edges, while females are rufous-brown with pale streaking on the neck, breast, and flanks. The subspecies hoogerwerfi tends to be more uniform, with less distinct streaking. Its vocalisations are relatively infrequent, consisting of soft contact calls such as “bub” or “keep,” while males perform a characteristic display involving audible wing-whirring at close range. The species is often regarded as an important indicator of montane forest health in Sumatra, given its sensitivity to deforestation and habitat fragmentation.

12. Sumatran Partridge/IUCN Status: Least Concern (LC)

Photo by Wikipedia

Arborophila sumatrana, or the Sumatran Partridge, is an endemic bird of Sumatra measuring around 28 cm in length and is considered monotypic. This species is regarded as rare to locally uncommon, with a restricted distribution in submontane forests in southern Sumatra, particularly south of the Batak Mountains and in the Simalungun region, at elevations of 500–1,500 meters. Its primary habitat consists of relatively intact primary and secondary forests, with a preference for dense forest floor cover. The species is terrestrial, typically encountered alone or in small groups, and exhibits secretive behaviour, making it difficult to observe in the wild (BirdLife International).

Morphologically, this species closely resembles Arborophila rolli (Roll’s Partridge) but can be distinguished by its grey head and neck, a darker brown crown and nape, and the presence of white patches on the cheeks and throat. The underparts are generally grey, with fairly prominent barring on the flanks. Its vocalisation is similar to other partridges within the genus, particularly resembling that of the Chestnut-bellied Partridge, consisting of repeated calls used for communication between individuals. The presence of this species is strongly influenced by the condition of intact forest habitats, making forest degradation a major threat to its long-term survival in the wild.

13. Sumatran Peacock-Pheasant/IUCN Status: Least Concern (LC)

Sumatran Peacock-Pheasant/Photo credit by  Zacky (Explore Kerinci).

Polyplectron chalcurum, or the Sumatran Peacock-Pheasant, is an endemic bird of Sumatra exhibiting clear sexual dimorphism, measuring around 65 cm in males and 46 cm in females. The species comprises two subspecies: chalcurum (southern to central Sumatra) and scutulatum (northern Sumatra), with the latter showing more pronounced barring on the upperparts. It is considered uncommon and inhabits primary submontane to montane forests at elevations of 800–1,800 meters, including forest edges with dense vegetation. The species is terrestrial, highly elusive, and typically encountered alone on the forest floor, with a strong preference for relatively undisturbed habitats (BirdLife International).

Morphologically, this species is characterised by a dark rufous-brown body with fine black barring across most of the plumage, except on the head and neck. Males possess a long and distinctive tail with metallic purple-blue panels on the outer feathers, while females have a shorter tail with smaller and less conspicuous panels; juveniles resemble females but lack the metallic panels on the tail. Its vocalisation is a loud, harsh call described as “OW-OW-ow,” lasting about 1.5 seconds, sometimes lacking the final note, as well as a sharp single call “WAK.” The species is highly sensitive to forest habitat degradation, and its presence is often regarded as an important indicator of montane forest ecosystem health in Sumatra.

References

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